Convenient synthesis of the immunogenic glycolipid BbGL1.

A simple and efficient method to synthesize the immunogenic glycolipid BbGL1 is introduced. Two simple steps were required to obtain the desired product in good yield. First, a highly efficient glycosylation of cholesterol using galactosyl trichloroacetimidate as a donor was performed to produce cholesteryl-ß-d-galactoside. Finally, an efficient palmitoylation on the C6-OH of the galactose of the synthesized saponin using sym-collidine and acyl chloride under microwave heating that produced BbGL1 in good yield. The procedure is a convenient and cheaper alternative to the reported procedures allowing a rapid preparation of multiple analogs and conjugates.

Evaluation of a rapid serological test for leprosy classification using human serum albumin as the antigen carrier.

The presence of anti-BSA antibodies may interfere in serological tests, as ELISA or immunochromatographic assays. BSA is frequently used as a blocking agent or as "inert" carrier of antigens, such as the NT-P-BSA, the semi-synthetic trisaccharide analogue of the PGL-I (phenolic glycolipid-I) antigen from the cell wall of the Mycobacterium leprae. PGL-I was prepared and linked to human serum albumin based in the hypothesis that replacing BSA by a human protein carrier would enhance the performance of leprosy serological tests. A total of 1162 serum samples were tested by ELISA and by the ML Flow rapid test using NT-P-BSA or NT-P-HSA antigens. When grouping leprosy patients as paucibacillary (PB) or multibacillary (MB) according to the Ridley & Jopling classification, ML Flow BSA and ML Flow HSA tests correctly allocated 70.9% and 68.6% of patients in the PB group, and 87% and 81% of patients in the MB group, respectively. Concordant results were found in 82.0% (953/1162) (kappa value=0.637; sd=0.023) of samples between ML Flow tests and 85.7% (996/1162) (kappa value=0.703; sd=0.021) between ELISA tests. ML Flow results were statistically similar and the same was true for ELISA tests using HSA or BSA. However, we noticed a tendency to decreased capacity to detect MB patients and an increased positivity among PB patients, HHC, TB patients and healthy controls by the HSA carrier in both ML Flow and ELISA. The PGL-I serology performed by the ML Flow test with BSA or HSA as antigen carriers can be a useful, friendly auxiliary tool to identify patients with higher bacterial load.

Multicomponent synthesis of Ugi-type ceramide analogues and neoglycolipids from lipidic isocyanides.

Unique types of ceramide and glycolipid architectures were obtained by means of Ugi reactions incorporating lipidic isocyanides as surrogates of sphingolipids. The multicomponent nature of this approach allowed for a highly efficient assembly process, wherein two of the components provided the lipidic tails while a third one incorporated either the functionality suitable for the conjugation to sugar or the sugar moiety itself. Two dissimilar strategies were implemented: (i) the initial assembly of ceramide analogues followed by glycosylation to produce a glycolipid skeleton and (ii) the one-pot construction of glycolipid frameworks by condensation of lipidic isocyanides either with lipidic amines and oligosaccharidic acids or with fatty acids and oligosaccharidic amines. Whereas both approaches are amenable for accessing analogues of anticancer glycolipids, the latter one proved to have greater potential owing to its more straightforward and efficient character. Overall, the methodology developed shows great promise toward the massive (eventually combinatorial) production of neoglycolipids suitable for biological screening.

Phenolic glycolipid-1 (PGL-1) in buruli ulcer lesions. First demonstration by immuno-histochemistry

Buruli ulcer, caused by Mycobacterium ulcerans, is emerging as the third most common mycobacterial disease after leprosy and tuberculosis in some tropical regions. Although a toxin of the polyketide family is central to the pathogenesis of the disease, there are still several parameters that need clarification. Among them and of crucial interest are the curative drug treatment and the test for early detection of the disease. In this study, we used mouse monoclonal antibodies, raised against synthetic sugars of the terminal trisaccharide of M. leprae PGL-1, to detect the immunoreactivity of this antigen in tissue infected with M. ulcerans. Thirty specimens of skin tissue from Buruli ulcer patients (3 plaques, 10 nodules, 1 ulcerated nodule, 7 deep ulcer beds and 9 ulcers in healing) were obtained from Ghana. Eighty-three percent of the submitted cases were compatible with the lesions of Buruli ulcer. AFB were positive in 33% of plaques, 40% of nodules, 44% of actives ulcers and 22% of the ulcer in healing stage. Immunohistochemically, phenolic glycolipid-1 (PGL-1) was detected in all AFB-positive cases. This observation implies that Mycobacterium ulcerans may express an M. leprae PGL-1-like substance and should tentatively emulate research to further characterize such a substance. The search for an early diagnostic tool for the Buruli disease may benefit from such investigations.